WASHINGTON – Wind energy facilities have killed at least 67 golden and bald eagles in the last five years, but the figure could be much higher, according to a new scientific study by government biologists.
The research represents one of the first tallies of eagle deaths attributed to the nation’s growing wind energy industry, which has been a pillar of President Barack Obama’s plans to reduce the pollution blamed for global warming. Wind power releases no air pollution.
But at a minimum, the scientists wrote, wind farms in 10 states have killed at least 85 eagles since 1997, with most deaths occurring between 2008 and 2012, as the industry was greatly expanding. Most deaths – 79 – were golden eagles that struck wind turbines. One of the eagles counted in the study was electrocuted by a power line.
The vice president of the American Bird Conservancy, Mike Parr, said the tally was “an alarming and concerning finding.”
A trade group, the American Wind Energy Association, said in a statement that the figure was much lower than other causes of eagle deaths. The group said it was working with the government and conservation groups to find ways to reduce eagle casualties.
Still, the scientists said their figure is likely to be “substantially” underestimated, since companies report eagle deaths voluntarily and only a fraction of those included in their total were discovered during searches for dead birds by wind-energy companies. The study also excluded the deadliest place in the country for eagles, a cluster of wind farms in a northern California area known as Altamont Pass. Wind farms built there decades ago kill more than 60 per year.
“It is not an isolated event that is restricted to one place in California, it is pretty widespread,” said Brian Millsap, the national raptor coordinator for the U.S. Fish and Wildlife Service, and one of the study’s authors.
The study excluded 17 eagle deaths for which there was not enough evidence. And, in a footnote, it says more golden and bald eagles have since been killed at wind energy facilities in three additional states – Idaho, Montana and Nevada.
It’s unclear what toll the deaths could be having on local eagle populations. And while the golden eagle population is stable in the West, any additional mortality to a long-lived species such as an eagle can be a “tipping point,” Millsap said.
Wind farms are clusters of turbines as tall as 30-story buildings, with spinning rotors as wide as a passenger jet’s wingspan. Though the blades appear to move slowly, they can reach speeds up to 170 mph at the tips, creating tornadolike vortexes.
Wind farms in two states, California and Wyoming, were responsible for 58 deaths, followed by facilities in Oregon, New Mexico, Colorado, Washington, Utah, Texas, Maryland and Iowa.
In all, 32 facilities were implicated. One in Wyoming was responsible for a dozen golden eagle deaths, the most at a single facility.
The research was published in the Journal of Raptor Research.